Decorative panel having a digitally printed pattern and printing method therefor

ABSTRACT

Disclosed is a method of producing a pattern for a decorative panel. The method includes applying a clear gel coat on a mold to form a clear layer. The clear layer is cured and then digitally printed with one or more inks so as to produce a pattern on the clear layer. Also disclosed is a decorative panel including a clear layer, an opaque layer and a pattern digitally printed on the clear layer, between the clear and opaque layers, such that the pattern is visible through the clear layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of and priority to U.S. provisionalpatent application No. 61/856,150, filed Jul. 19, 2013, the contents ofwhich are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to decorative panels, and moreparticularly to decorative panels having a digitally printed pattern anda method for printing same.

BACKGROUND

Decorative panels and tiles are commonly used to cover floors, walls oreven shower walls for example. Tiles are usually secured on a surfaceusing glue and cement and grout is used to fill up space between thetiles. In most instances, grout lines are visible between the tilesafter the tiles have been installed.

Installing tiles may be relatively expensive, labor intensive and/ortime consuming. Accordingly, decorative panels are sometimes provided asan alternative. This type of panels typically comprises a face whichlies against the wall of a structure and an opposite decorative face inwhich a plurality of grooves or recesses are defined to simulate groutlines or other indented patterns or textures.

Different alternatives have been proposed to manufacture indenteddecorative panels. For instance, United States patent applicationpublished under No. 2008/0115437 to Bordener discloses an indented panelmanufactured using a base panel made of plastic resin in which arecreated a plurality of indented grid lines using a cutting tool such asa router. U.S. Pat. No. 5,052,160 to Gentsch et al. discloses a similarpanel, except that the indented lines are created in the plastic resinusing a tubular heater instead of a cutting tool. U.S. Pat. No.4,169,907 to Barker et al. discloses a panel comprising a hardboardsubstrate on which a pattern is drawn using ink. A liquid top coat isthen applied over the ink and the hardboard substrate. The ink repelsthe liquid top coat to form “valleys” on the panel. Since the liquid topcoat is thinner over the portions of the substrate which are covered inink, the ink is visible through the top coat.

Other types of decorative panels can also be used. For example, solidsurface panels, such as cultured marble panels or cultured granitepanels, are sometimes used to imitate a natural smooth or texturedsurface. These panels can be manufactured by molding resin, which may bemixed with pigments and/or fillers.

The manufacturing of most of these panels is relatively expensive,relatively complicated, relatively labor intensive and/or relativelytime consuming. Furthermore, the panels manufactured using such methodsare often disregarded as being true alternative to the surface they areaimed to imitate because of their unnatural visual appearance.

There is therefore a need for a decorative panel that has a naturalvisual appearance and for a method for manufacturing such a panel whichis relatively inexpensive, relatively easy and relatively fast.

Features of the invention will be apparent from review of thedisclosure, drawings and description of the invention below.

BRIEF SUMMARY

We have developed a method of digitally printing a pattern onto a panel,which is considerably more accurate than conventional methods becausethe inks used may be applied with more precision than conventionalmethods.

According to one aspect, there is provided a method of producing apattern for a decorative panel, the method comprising:

-   -   applying a first gel coat on a mold to form a first layer, the        first gel coat and the first layer being clear;    -   curing the first layer;    -   digitally printing one or more inks onto the cured first layer        to produce a first pattern thereon.

In one example, the mold has a second pattern thereon, the first patternprinted on the first layer matching the second pattern.

In one example, the first layer is cured by exposing the first layer toelectron beam, ultraviolet light or heat, or is cured by the previousaddition of a catalyst. A combination of any previous can also be used.

In one example, the method further comprises curing the printed one ormore inks.

In one example, the one or more inks are cured by exposing the inks toultraviolet light.

In one example, the first gel coat is applied by spraying the first gelcoat over substantially the entire surface of the mold.

In one example, the mold includes a textured surface, the first layerbeing formed on the textured surface.

In one example, the first pattern matches the textured surface.

In another example, the mold includes a smooth surface.

In one example, the method further comprises applying a second gel coaton the digitally printed first layer to form a second layer on thedigitally printed first layer.

In one example, the second gel coat and the second layer are opaque.

In one example, the second layer is applied by spraying the second gelcoat over substantially the entire surface of the digitally printedfirst layer.

In one example, the method further comprises curing the second layer.

In one example, a catalyst is mixed in the second gel coat so as toactivate the curing of the second layer.

In one example, the first layer has a thickness ranging from 0.001 to0.100 inches (0.0254 mm to 2.54 mm). In another example, the first layerhas a thickness ranging from 0.005 to 0.03 inches (0.127 mm to 0.761mm). In yet another example, first layer has a thickness ranging from0.01 to 0.02 inches (0.254 mm to 0.508 mm). In a preferred example, thefirst layer has a thickness of about 0.014 inches (0.356 mm).

In one example, the second layer has a thickness ranging from 0 to 0.05inches (0 mm to 1.27 mm). In another example, the second layer has athickness ranging from 0.005 to 0.03 inches (0.127 mm to 0.761 mm). Inyet another example, the second layer has a thickness ranging from 0.01to 0.02 inches (0.254 mm to 0.508 mm). In a preferred example, thesecond layer a thickness of about 0.015 inches (0.381 mm).

In one example, the curing of the second layer takes place for about 30to 50 minutes.

In another example, the curing of the second layer takes place for about40 minutes.

In one example, a digital printer is pre-programmed to apply the inks tomatch the second pattern on the mold.

In one example, the method further comprises applying reinforcementmaterial on the second layer to form a reinforcement layer on the secondlayer.

In one example, the reinforcement material is applied by spraying thereinforcement material over substantially the entire surface of thesecond layer.

According to another aspect, there is also provided a decorative panelcomprising:

-   -   a first layer defining a front of the decorative panel, the        first layer being clear;    -   a second layer covering substantially the entire surface of the        first layer;    -   a first pattern located between the first and second layer, the        first pattern being digitally printed on one of the first layer        or the second layer and being visible through the first layer.

In one example, the second layer is opaque.

In one example, the decorative panel further comprises a reinforcementlayer covering substantially the entire surface of the second layer.

In one example, the first and second layers define a textured surface.

In another example, the first and second layers define a substantiallysmooth surface.

In one example, the first pattern imitates the appearance of a naturalmaterial.

In another example, the first pattern imitates the appearance of amanmade design.

In one example, the manmade design is selected from a group comprising atiled surface, brickwork and a stone wall surface.

In one example, the first layer has a matt or a glossy finish. Inanother example, the first layer has a partially matt or a partiallyglossy finish.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the herein described may be readily understood,embodiments are illustrated by way of example in the accompanyingfigures.

FIG. 1 is a flow diagram of a method of producing a pattern for adecorative panel, in accordance with one example;

FIG. 2 is a flow diagram of a method of manufacturing a decorative panelhaving a digitally printed pattern thereon, in accordance with oneexample;

FIG. 3A is a schematic side view of a printing head propelling ink on aclear layer in accordance with the method shown in FIG. 1, in which theprinting is unidirectional;

FIG. 3B is a schematic side view of a printing head propelling ink on aclear layer in accordance with the method shown in FIG. 1, in which theprinting is bidirectional;

FIG. 4 is a flow diagram of a method for producing a distorted image toproduce the pattern on the clear layer in accordance with the methodshown in FIG. 1;

FIG. 5 is a drawing of a digital image in which a position of one ormore reference features of the pattern is calculated, in accordance withthe method shown in FIG. 4;

FIG. 6A is a drawing of a measurement image created from the digitalimage shown in FIG. 5;

FIG. 6 B is an enlarged view of a portion of FIG. 6A;

FIG. 7 is a drawing of the measurement image of FIGS. 6A and 6B printedon a test clear layer;

FIG. 8 is a drawing of the measurement image of FIGS. 6A and 6B printedon the test clear layer, in which a required offset of referencefeatures of the digital image have been determined;

FIG. 9 is a cross-section view of a decorative panel having a digitallyprinted pattern, in accordance with one example; and

FIG. 10 is a photograph of a decorative panel, in accordance with oneexample, which includes a tiled surface in which each tile includes adifferent pattern to show examples of various digitally printedpatterns.

Further details of the invention and its advantages will be apparentfrom the detailed description included below.

DETAILED DESCRIPTION

In the following description of the embodiments, references to theaccompanying drawings are by way of illustration of an example by whichthe invention may be practiced. It will be understood that otherembodiments may be made without departing from the scope of theinvention disclosed.

Broadly speaking, a method is described in which a decorative panel isproduced by printing a pattern on a clear or transparent polymer layer,which is layered on top of a mold. The method of digitally printing apattern onto a panel, provides unequaled performance and visual resultscompared to conventional methods. The described method allows forimproved textured finish and slight 3D forms, more accurate inkplacement over textures and forms and resistant protective coating notcompromising textures capabilities.

The methods previously known in the art typically involve adding a clearcoat on top of a laminate comprising a back, support surface on which isprinted a pattern. Because such clear coating is generally liquid whenit is applied, it naturally tends to self-level over the surfaces onwhich it is applied and fill any surface irregularities. Therefore,obtaining natural textures such as wood grain or tile porosities tendsto be difficult, which often leads to unsatisfactory texture or visualappearance.

With the present method, the layer of clear or transparent polymer isformed on the mold and the additional panel layers are subsequentlybuilt on the clear coat. Because the clear coat is in direct contactwith the mold, it exactly reproduces the texture of the mold, thereforeavoiding the drawbacks generally associated with the self-levelingproperties of the clear coat. The present method thus provides morenatural visual characteristics and textures.

The method will be described with references to FIGS. 1 and 2.

1. Pre-Treatment

According to step 10, the method begins by preparing the mold and thenforming the clear layer on the mold before printing the pattern, inaccordance with step 12. The clear layer is formed on the mold byspraying a clear polymer gel coat over substantially the entire surfaceof the mold. Alternatively, the clear gel coat could be applied with anapplication tool such as a roller or could be poured into the mold suchthat the clear gel coat flows and spreads out over the mold to form theclear layer.

The mold could be textured and have a decorative pattern thereon. In oneexample, the mold is embossed and includes at least one relief elementwhich defines at least one corresponding relief element on the clearlayer when the clear layer is applied on the mold. The correspondingrelief element is a negative image of one relief element. For example,if the relief element of the mold is a ridge, the corresponding reliefelement created on the clear layer is a recess which is shaped and sizedcorrespondingly to the ridge. In one example, the pattern imitates theappearance of a manmade design, such as a tiled surface reproducing theappearance of a tiled shower wall for instance. Alternatively, thepattern may imitate the appearance of brickwork or of a stone wallsurface.

In one example, the corresponding relief element is shaped and sized tocorrespond to the pattern to be printed on the clear layer. Forinstance, the pattern may correspond to grout lines. In this case, theat least one corresponding relief element may be a recess which isshaped to provide the appearance of a grout line which would be formedbetween adjacent tiles of a tiled wall.

Alternatively, the mold could define a planar surface of a predeterminedsize and shape to create a planar panel of similar size and shape. Theplanar surface could be substantially smooth to produce a substantiallysmooth clear layer having a glossy appearance, or fine-textured so as togive a matte appearance to the clear polymer layer. The pattern couldimitate the appearance of a natural surface, such as marble, granite orwood.

In one example, the mold is formed using a base model, which includes apanel base and a plurality of tiles or other elements of a manmadedesign (e.g. bricks or stones) which are secured on the panel base. Thepanel base may be made of wood or any other material that a personskilled in the art would deem fit for this purpose. The base model isthen molded to create a reference mold, which includes all the featuresof the mold. The reference mold is then used to mold a master model ormaster plug, which includes all the features of the base model. Thiswill allow the master model to be used to make at least one mold. Itwill be appreciated that the master model can be used to make aplurality of molds to facilitate the manufacturing of decorative panelsin a relatively large quantity.

In one example, the clear gel coat is added to a thickness of about0.001 to 0.100 inches (0.0254 mm to 2.54 mm). In another example, thegel coat is added to a thickness of 0.005 to 0.03 inches (0.127 mm to0.761 mm). In yet another example, the gel coat is added to a thicknessof 0.01 to 0.02 inches (0.254 mm to 0.508 mm). In a preferred example,the gel coat is added to a thickness of about 0.014 inches (0.356 mm).Alternatively, the clear gel coat could be added to another thicknessbased on the desired physical properties of the gel coat and/or panel,including resistance to abrasion, thermal shocks, physical impacts andthe like.

The term “clear gel coat” as used herein is intended to mean any coatingor material that is at least partially transparent so as to enablevisual perception of the ink and/or opaque gel coat applied to the clearcoat, once the panel manufacture is complete and the panel is installedon a surface. The person skilled in the art will appreciate that theclear gel coat can therefore be completely transparent (i.e. the gelcoat has no color) or be tinted or colored. In the latter case, theclear coat color will collaborate with the color of the ink and thecolor of the opaque coat applied subsequently to provide the panel withits final color. The term “clear gel coat” as intended herein thereforeincludes materials such as acrylic resins, vinyl ester resins,polyurethane resins, polyester resins and the like.

The person skilled in the art will appreciate that the gel coat of thepanel may have a glossy or mat finish once unmolded, depending on thenature or type of the clear coat used, as well as of the configurationof the mold.

Examples of clear gel coats suitable for the purpose of manufacturing apanel according to the current method include gel coats such as thosecommercialized by CCP Composites Canada (Brampton, Ontario, Canada),AOC® (Collierville, Tenn.), Ashland Inc. (Covington, Ky.) and Valspar(Minneapolis, Minn.). As it will be appreciated, other suitable cleargel coats could also be used.

In one example, a photoinitiator may be added to the gel coat toinitiate the polymerization process. Examples of photoinitiator suitablefor the purpose of manufacturing panels according to the present methodincludes Bis Acyl Phosphine Oxide (BAPO) type of photoinitiator likeBASF's CIBA® photoinitiators of the Irgacure® series, as well as MEKPcatalyst commercialized by Eager Polymers (Chicago, Ill.). It willhowever be understood that any photoinitiator capable of initiating,speeding or otherwise facilitating UV curing of the clear gel coat couldbe used, as well as a co-initiated mixture of previous initiators.

In one example, the photoinitiator can be used in a concentrationranging from 0.05% to 2.0% (w/w). As it will be appreciated by theperson skilled in the art, the concentration of photoinitiator used incombination with the clear coat resin will vary according to the clearcoat type and composition, the type of photoinitiator, the desired UVcuring properties (e.g. curing time, moisture content, clear coatfirmness). As such, the photoinitiator concentration will be adjusted oroptimized according to such parameters, using methods known by thoseskilled in the art.

2. First Curing

According to step 14, the clear layer is cured by exposing the substrateto ultraviolet light or some conventional means of curing known to thoseskilled in the art, such as exposing the clear layer to heat or to anelectron beam.

In one example, the clear layer is cured using a UV light expositionvarying from 180 to 2000 mill joules per square centimeter (mJ/cm²). Theperson skilled in the art will however appreciate that depending on thedesired cure time, the type and concentration of photoinitiator (ifany), the type of clear coat and the desired properties of the gel coat,other UV light expositions could be used.

Examples of suitable UV curing lamps suitable for the purpose ofcarrying out the present method include UV curing flood lamps, UVconveyors and UV lamps mounted to CNC apparatuses. As it will beappreciated by a person skilled in the art, the UV light exposition(mJ/cm²) will vary based on the distance between the UV lamp and thesurface to be cured, the intensity of the UV lamp in watt per inch (wpi)and the exposure time, which itself can vary depending on thedisplacement speed of the UV curing lamp relative to the surface to becured.

In one example, the clear layer is cured for about 10 minutes to about 3days, and preferably between 30 minutes and 1 day, and more preferablybetween 30 and 75 minutes.

As it will be appreciated by the person skilled in the art, the curingtime for the first curing will vary according to the clear coat type andcomposition, the type of photoinitiator, the desired UV curingproperties (e.g. curing time, moisture content, clear coat firmness), aswell as the characteristics of the UV lamp system used. This personskilled in the art will also appreciate that such parameters can beadjusted according to known methods.

3. Digital Printing

According to step 16, a decorative pattern is produced on the curedclear layer by digitally printing one or more inks onto the cured clearlayer. In one example, the digitally decorative pattern matches thepattern on the mold (e.g. grout lines).

The digital printing of the decorative pattern on the cured clear layermay take place sometime after curing thereof, to ensure that thephysical and chemical properties of the clear layer are adequate toreceive the ink. In one example, the digital printing of the decorativelayer takes place between 5 minutes and 10 days after curing of theclear layer. In another example, the digital printing of the decorativelayer takes place between 10 minutes and 8 days after curing of theclear layer. In yet another example, the digital printing of thedecorative layer takes place between 10 minutes and one day after curingof the clear layer. In a preferred example, the digital printing of thedecorative layer takes place between 10 minutes and 120 minutes aftercuring of the clear layer.

The digital printing of the decorative pattern includes inkjet printing,which may be performed using an inkjet printer. Typically, the inkjetprinter comprises a printing head which is adapted to propel droplets ofink on the clear layer. Specifically, the printing head comprises aplurality of nozzles which are adapted to be oriented so as to propelink towards the clear layer. Alternatively, the inkjet printer mayinclude a plurality of printing heads instead of a single printing head.Examples of inkjet printers suitable for carrying out the method includeAcuity HF™ wide format printer (Fujifilm, Tokyo, Japan), Agfa Graphics™wide format high-speed curable inkjet systems (Agfa Graphics,Mississauga, Ontario, Canada), HP Scitex™ printers (Hewlett-PackardCompany, Palo Alto, Calif.), Xerox® wide format printers (Xerox,Norwalk, Conn.) and Canon® Océ Arizona™ printers (Canon, Mississauga,Ontario, Canada). The person skilled in the art will appreciate thatmany wide format inkjet printers and CMYK presses exist and that anysuch suitable printers or CMYK presses could be used without departingfrom the purpose of the current method.

The printing includes positioning the printing head at a printingdistance from the at least one relief element. The printing distance isselected to allow the pattern to have a desired resolution so as toprovide a desired appearance to a user, such as a tiled appearance. Asit will be appreciated, the printing distance between a portion of apanel (e.g. a first relief element) can be different than the printingdistance between another portion of the same panel (e.g. a second reliefelement). In one example, the printing distance between the printinghead and a portion of the clear surface is less than 8 mm. In a furtherexample, the printing distance between the printing head and the portionof the clear surface is between 0.1 mm and 5 mm. In a preferred example,the printing distance between the printing head and the portion of theclear surface is between 1.5 and 4.0 mm. It has been found that at thisprinting distance, the printing would produce a relatively sharppattern.

In one example, the ink used to carry out the method is a UV curableink. Exemplar of suitable ink includes Fujifilm Uvijet KO and KI seriesUV curable inks (Fujifilm, Tokyo, Japan), Anapurna™, Anuvia™ and Agora™UV curable inks (Agfa Graphics, Mississauga, Ontario, Canada), HP 250Scitex™ Ink (Hewlett-Packard Company, Palo Alto, Calif.), Wide FormatIJP 2000™ Ink (Xerox, Norwalk, Conn.) or any ink suitable for use withspecific wide format printers, according to the technical specificationsof such printers.

As it will be appreciated, the coverage density of the ink over theclear layer (i.e. the proportion or percentage of clear layer covered bythe digitally printed ink) will vary depending on the printed pattern.In one example, the ink coverage density varies between 0% and 100%. Itwill also be appreciated that multiple layers of ink can be applied onthe clear layer, and that such multiple layers of ink may overlap eachother partially and or totally, depending on the desired colorintensity.

For instance, on a CMYK press, using cyan and magenta inks at both 100%would result in a 200% coverage with a vibrant red color. In anotherexample, rich black would be produced by combining 75% cyan, 68%magenta, 67% yellow and 90% key (black), which would result in a 300%coverage. In such a case, the ink coverage would thus exceed 100% theclear surface. By way of an example, an ink coverage density of 200%would indicate that the clear layer is covered by two layers of ink,each ink layer covering the entire surface of the clear layer, and anink coverage density of 150% would indicate that a first ink layercovers the entirety of the clear layer while a second ink layer would beapplied on 50% of the clear layer. Alternatively, a 150% ink coveragedensity could indicate that two ink layers each cover 75% of the clearsurface. Therefore, in one example, the ink coverage density could varybetween 0% and 400% of the clear layer. In another example, the inkcoverage density could vary between 0% and 280%.

In one example, the size of the printing head is smaller than the clearlayer surface. Specifically, digitally printing the clear layer requiresthe print head to be displaced along a printing plane coplanar with theclear layer. The printing plane could be located above the clear layerand the printing head could be configured to propel ink generallydownwardly towards the clear layer. To apply ink over a desired portionof the clear layer to form the pattern, the print head is displacedalong a predetermined printing path defined in the printing plane. Theprinting plane is at the printing distance from the clear polymer layer,such that the printing head may remain at the predetermined printingdistance throughout the whole printing operation. This allows theprinting head to apply the ink to form a pattern which has a relativelyuniform resolution.

In one example, the predetermined printing path is serpentine.Specifically, the area of the printing plane above the clear layer isdivided into a plurality of adjacent strips of similar width, whichcorrespond to a width covered by the printing head. The printing head isfirst displaced linearly along a first strip in a first direction. Whilebeing displaced along this first strip, the printing head prints a firstportion of the pattern corresponding to the first strip. When theprinting head arrives to the end of the first strip, the printing headis displaced transversely until it is aligned with a second strip,adjacent the first strip. The printing head is then displaced along thesecond strip in a second direction opposite the first direction. Whilebeing displaced along this second strip, the printing head prints asecond portion of the pattern corresponding to the second strip. This isrepeated until the entire surface of the clear layer is covered and theentire pattern is printed. This allows the entire surface of the clearlayer to be covered relatively efficiently.

In another example, the printing head is configured for unidirectionalprinting (see for instance, FIG. 3A. Specifically, the printing headonly prints on the clear layer when it is displaced in the firstdirection. In this example, the printing head is first moved along thefirst strip in the first direction from a first side to an opposite sideof the clear layer while printing on the clear layer. The printing headis then moved back along the first strip to the first side withoutprinting on the clear layer. The printing head is then movedtransversely until it is aligned with the second strip. The printinghead is then displaced towards the opposite side of the clear layeralong the second strip while printing on the clear layer. This processis repeated until the entire pattern is printed on the clear layer.

Alternatively, the printing head could be displaced along the firststrip to the opposite side of the clear layer while printing, movedtransversely until it is aligned with the second strip, and then movedalong the second strip towards the first side of the clear layer withoutprinting on the clear layer. The printing head could then be moved backtowards the opposite side while printing on the clear layer. Thisprocess could be repeated until the entire pattern is printed on theclear layer. It will be appreciated that various other printingsequences are also possible.

In an alternative example, the printing head could be stationary and themold could be moved relative to the printing head, or the mold and theprinting head could both be moved relative to each other.

In one example, the printing head is displaced further than the end ofthe strip along which it is travelling. Specifically, the predeterminedpath of the printing head includes a first portion which is locatedabove the clear layer and a second portion, corresponding to transversemovement of the printing head from one strip to an adjacent strip, whichis laterally offset relative to the clear layer. This allows theprinting head to travel all the way to the edges of the panel, in orderto print portions of the pattern which are located at or near the edgesof the panel.

Alternatively, the printing head could be large enough to print thepattern on the entire desired portion of the clear polymer layer,without having to displace the printing head. In one example, the inkjetprinter could include a plurality of printing heads arranged so as tocover the entire clear layer in a single pass.

In one example, the printing further includes printing only on the atleast one relief element. For example, if the relief element is a ridgeas explained above, ink will only be applied on a top surface of theridge.

Alternatively, the printing of the clear layer further includes printinga first pattern portion on the at least one relief element and a secondpattern portion on an area of the clear layer adjacent the at least onerelief element. For example, ink could be applied directly on a flatportion of the clear layer to form a streaked pattern having theappearance of a marbled surface, as well as on the top surface of theridges which would define a tiled pattern on the decorative panel. Theresulting panel would therefore have the appearance of a marble tiledsurface.

In one example, the inkjet printer is pre-programmed to apply the inksto match the first pattern on the panel substrate. In one example, thedigital printer comprises a controller. A digital image of the patternis inputted into the controller, which controls the digital printeraccordingly to produce the printed pattern on the cured clear layer. Thedigital image could be in any digital format known to the skilledaddressee.

FIG. 3A shows a printing head 40 propelling ink on a clear layer 42cured on a mold 41, in accordance with one example. In this example,during printing, ink is propelled forward of the printing head 40 andobliquely relative to the clear layer 42 to account for the displacementD₁ of the printing head 40. Specifically, the printing head 40 is setsuch that ink is propelled from one of the nozzles 44 a-44 d at apredetermined angle θ₁ to a first target point T₁ on the clear layer 42which is forward of the nozzle (e.g. forward of nozzle 44 a) relative toa displacement direction of the printing head 40. The predeterminedangle θ₁ could be selected according to a displacement speed of theprinting head, for instance.

To print on the first target point T₁ located on a top surface of aridge 46, the ink is propelled from the nozzle (e.g. nozzle 44 a)forwardly at a first horizontal offset distance O₁ from the position ofthe nozzle. To print on a second target T₂ which is located on a plane48 below the plane defined by the top surface of the ridge 46, the inkis propelled from the nozzle (e.g. nozzle 44 a) forwardly at a secondhorizontal offset distance O₂. Since the predetermined angle θ₁ at whichthe ink is propelled forwardly remains constant, the second offsetdistance O₂ is greater than the first offset distance O₁, as shown inFIG. 3A. Therefore, in this example, the digital image inputted into thecontroller can be distorted or warped according to a tridimensionalprofile of the clear layer, which corresponds to the tridimensionalprofile of the mold. The distortion or warping can depend on differentfactors, such as the height, shape and position of the ridges, or of anyother tridimensional element of the clear layer. The distortion orwarping can also depend on the printing distance and on the displacementspeed of the printing head.

Alternatively, the printing head 40 may be configured for bidirectionalprinting, as seen in FIG. 3B. In this example, the printing head 40 maypropel ink at a first predetermined angle θ₁ when displaced in the firstdirection D₁ and may propel ink at a second predetermined angle θ₂ whendisplaced in the second direction D₂ opposite the first direction D₁. Asshown in FIG. 3B, the second predetermined angle θ₂ is similar to thefirst predetermined angle θ₁, but is defined in the opposite direction,such that the second predetermined angle θ₂ is substantially a mirrorimage of the first predetermined angle θ₁. In this example, the digitalimage is distorted according to this configuration.

In another example, the printing head 40 could instead be mounted on amultiaxis machine to control the position and orientation of theprinting head 40 relative to the clear layer. In this configuration, thepattern could be printed on the clear layer directly based on thedigital image without requiring a distorted image.

Referring now to FIG. 4, a method for producing a distorted image whichwill produce the pattern once inputted in the controller and printed onthe clear layer will be described.

In this example, the digital image representing the pattern to beprinted is first provided. According to step 100, a position of one ormore reference features of the pattern is then calculated. In theexample illustrated in FIG. 5, the pattern 120 includes a tiled patternincluding a plurality of tile elements 122 a-122 f separated by verticalgrout line elements 124 a-124 c and horizontal grout line elements 126a-126 c. In this example, the reference features include the fourcorners (e.g. corners 146 a-146 d) of each tile element 122 a-122 f.This position may include Cartesian coordinates of the one or morefeatures relative to one or more reference locations. Alternatively,other means of defining a position may be used.

According to step 102, a measurement image is then created. Themeasurement image includes the pattern from the digital image and aplurality of reference markers disposed at a predetermined locationrelative to the reference features of the pattern. In the exampleillustrated in FIGS. 6A and 6B, each grout line element 124 a-124 c and126 a-126 c includes a centerline (e.g. centerlines 160 or 162) which ismarked on the measurement image, and the reference markers include aplurality of spaced-apart reference lines offset from this centerline(e.g. offset lines 166 a-166 h).

According to step 104, the measurement image is then printed on a testclear layer, as shown by the shadowed areas 170 a-170 c and 172 a-172 cin the grout line elements 124 a-124 c and 126 a-126 c, best shown inFIG. 7. The test clear layer will not be used to manufacture adecorative panel, but is merely used to produce the distorted image. Asexplained above, the clear layer includes a plurality of ridges formedby corresponding ridges defined on the mold. In this example, the groutlines of the pattern are designed to be printed on the top surface ofthe ridges. Alternatively, the measurement image could be printeddirectly on the mold.

According to step 106, the test clear layer with the printed measurementimage is then used to determine a required offset of the referencefeatures in order for those features to be aligned with the ridges whenprinted on the clear layer, as shown in FIG. 8. In the illustratedexample, an operator can determine a position of the boundaries of thegrout lines relative to the centerline of the grout line by visuallyassessing on which reference line each boundary lines up. Since thedistance between the reference lines is known, this allows the operatorto modify the digital image by applying a correction factor (e.g.correction factors 168 a-168 d in FIG. 8) and to produce the distortedimage, according to step 108.

This method therefore provides relatively simple means for an operatorto produce the distorted image based on the digital image representingthe pattern to be printed. This allows the pattern to be printed on thetop surfaces of the ridges, for instance. In one example, a firstportion of the pattern is printed on the ridge and a second portion ofthe pattern is printed on a flat portion of the clear layer adjacent theridge, which serves as the reference feature.

Alternatively, other means of producing a distorted image which, whenprinted on the clear layer, produces a desired pattern can be used.

For example, a sensor could be used to map a tridimensional profile ofthe clear layer, and the distorted image could be produced based on thismapped profile. The pattern could also include a plurality of colorpatterns which, when printed on the clear layer, overlap each other atleast partially to form the pattern. Each color pattern could be printedseparately and be produced using a corresponding distorted image.

4. Second Curing

Referring back to FIG. 1, the one or more inks digitally printed on theclear layer is then cured. In this step, the inks are exposed toultraviolet radiation for sufficient time to cure them. In one example,the digitally printed clear layer is exposed to UV light 100 mJ/cm² to2000 mJ/cm². The person skilled in the art will appreciate that exposingthe digitally printed clear layer to UV light may not be required. Insuch a case, the ink on the surface of the digitally printed clear layercould be allowed to dry at a defined temperature for a determined amountof time, prior to the subsequent application of the opaque gel coat. Inone example, the ink is allowed to dry for a period of 1 minute to 10days. In another example, the ink is allowed to dry for a period rangingfrom 5 minutes to 8 days. In yet another example, the ink is allowed todry for a period ranging from 5 minutes to 120 minutes.

In one example, the ultraviolet radiation is emitted by a UV lightsource, which is located next to the printing head containing thenozzle. In one example, the UV exposure of the ink to be cured ismodulated by adjusting the travel time of the ink layer relative to UVlight source, similarly to the UV cure of the clear layer. In anotherexample, the UV exposure of the ink to be cured is modulated byadjusting the intensity of the UV light source rather than theexposition time.

5. Second Gel Coat Application

Referring now to FIG. 2, once the printed clear layer is cured it isthen treated with an opaque gel coat which forms an opaque layer,according to step 22. This is achieved by spraying an opaque gel coatover substantially the entire surface of the printed and cured clearlayer. The ink digitally printed on the clear layer is now sandwichedbetween the clear and opaque layers.

The term “opaque gel coat” as used herein is intended to mean anycoating or material that is at least partially opaque so as to provide avisual barrier behind the clear coat layer and the digitally printedink, once the panel manufacture is complete and the panel is installedon a surface. The person skilled in the art will appreciate that theopaque gel coat can therefore be completely opaque or be partiallyopaque. In one example, the opaque gel coat has a white color. Inanother example, the opaque gel coat has another color. In yet anotherexample, the opaque gel coat color will collaborate with the color ofthe ink and the color of the clear coat applied previously to providethe panel with its final color. The term “opaque gel coat” as intendedherein therefore includes materials such as acrylic resins, vinyl esterresins, polyurethane resins, polyester resins and the like.Non-limitative examples of suitable opaque gel coats include opaque gelcoats commercialized by CCP Composites Canada (Brampton, Ontario,Canada), AOC® (Collierville, Tenn.), Ashland Inc. (Covington, Ky.) andValspar (Minneapolis, Minn.).

In one example, the opaque gel coat is added such that the second layermade of opaque gel coat has a thickness ranging from 0 to 0.05 inches (0mm to 1.27 mm). In another example, the layer of opaque gel coat has athickness ranging from 0.005 to 0.03 inches (0.127 mm to 0.761 mm). Inyet another example, the second layer has a thickness ranging from 0.01to 0.02 inches (0.254 mm to 0.508 mm). In a preferred example, thesecond layer has a thickness of about 0.015 inches (0.381 mm).

The opaque gel coat may be colored in any color, specifically in a colorwhich would contrast with the pattern. Alternatively, instead of opaquegel coat, a clear gel coat may be sprayed on the clear layer to formanother clear layer.

6. Third Curing

According to step 24, the opaque layer is then cured. The opaque gelcoat may be cured using a catalyst, such as a peroxide-based catalyst,which is mixed in the opaque gel coat so as to activate the curing. Anexample of a suitable catalyst is Luperox® DDM-9 catalyst commercializedby Arkema Inc. (Philadelphia, Pa.), but any other suitable catalystcould be used for the purpose of the present method. In one example, theconcentration of catalyst varies between 1.5% and 1.8% (w/w). In oneexample, the opaque layer is cured for about 30 to 50 minutes. In apreferred example, the opaque layer is cured for about 40 minutes.Alternatively, the opaque layer may include a photoinitiator and becured by exposition to ultraviolet light. In one example, the opaquelayer is cured using a UV light exposition varying from 180 to 4000mJ/cm². For a complete cure, the opaque layer may be exposed toultraviolet light using a UV light exposition varying from about 2000 to4000 mJ/cm².

7. Reinforcement and Further Processing

After applying the opaque layer, a reinforcement layer is applied overthe opaque layer, in accordance with step 26. In one example, thereinforcement layer includes resin and glass fibers.

According to step 28, the reinforcement layer is then laminated.

According to step 30, the reinforcement layer is then cured usingconventional means. The reinforcement layer may also include a catalystfor promoting the curing of the reinforcement layer. In one example, thereinforcement layer is cured for about 60 minutes. At this step, thedecorative panel is substantially formed in the mold.

According to step 32, the decorative panel is then removed from the moldor unmolded.

According to step 34, the decorative panel may then be trimmed to removeexcess material from the decorative panel.

The decorative panel may then be further processed and/or treated. Forinstance, the decorative panel may be inspected, undergo qualitytesting/inspection, be assembled in a kit including a plurality ofdecorative panels, be packaged and/or stored.

After the decorative panel is removed from the mold, the mold could bere-used to produce another decorative panel, or a plurality of similardecorative panels. In one example, a plurality of different molds couldbe manufactured, and each mold could be designed to produce acorresponding decorative panel. Each mold could have an identifier, suchas a barcode or an RFID tag, and a sensor could be used to identify themold based on this identifier. The inkjet printer could then select andprint a pattern associated with the decorative panel corresponding tothe mold identified.

It will be appreciated that all steps of the method may be performed atthe same location. Alternatively, some steps of the method could beperformed at one location while other steps of the method may beperformed at another location.

FIG. 9 shows a cross-section of a finished decorative panel 200 on amold 250, in accordance with one embodiment. A pattern 202 is digitallyprinted on a clear layer 204 and an opaque layer 206 coverssubstantially the entire surface of the clear layer 204, such that thepattern 202 is sandwiched between the clear and opaque layers 204, 206.When the decorative panel 200 is removed from the mold 250, the clearlayer 204 defines a front of the decorative panel 200 and provides aninterface between the panel and the environment. Since the clear layer204 is clear or transparent, the pattern 202 is visible through theclear layer 204. On the illustrated example, the decorative panel 200further includes a reinforcement layer 208 which substantially coversthe entire surface of the opaque layer 206.

FIG. 10 shows an example of a decorative panel, which includes a tiledsurface in which each tile includes a different pattern, to showcaseexamples of patterns which could be printed using the method describedabove. It will be appreciated that all the illustrated patterns could beprinted in a single printing operation using this method. Various otherpatterns could be produced using the method described above.

Although the above description relates to a specific preferredembodiment as presently contemplated by the inventor, it will beunderstood that the invention in its broad aspect includes mechanicaland functional equivalents of the elements described herein.

What is claimed is:
 1. A method of producing a pattern for a decorativepanel, the method comprising: applying a first gel coat on a mold toform a first layer, the first gel coat and the first layer being clear;curing the first layer; digitally printing one or more inks onto thecured first layer to produce a first pattern thereon.
 2. The method,according to claim 1, in which the mold has a second pattern thereon,the first pattern printed on the first layer matching the secondpattern.
 3. The method, according to claim 1, in which the first layeris cured by exposing the first layer to ultraviolet light or heat. 4.The method, according to claim 1, further comprising curing the printedone or more inks.
 5. The method according to claim 4, in which the oneor more inks are cured by exposing the inks to ultraviolet light.
 6. Themethod, according to claim 1, in which the clear gel coat is applied byspraying the first gel coat over substantially the entire surface of themold.
 7. The method, according to claim 1, in which the mold includes atextured surface, the first layer being formed on the textured surface.8. The method, according to claim 7, in which the first pattern matchesthe textured surface.
 9. The method, according to claim 1, in which themold includes a smooth surface.
 10. The method, according to claim 1,further comprising applying a second gel coat on the digitally printedfirst layer to form a second layer on the digitally printed first layer.11. The method, according to claim 10, in which the second gel coat andthe second layer are opaque.
 12. The method, according to claim 10, inwhich the second layer is applied by spraying the second gel coat oversubstantially the entire surface of the digitally printed first layer.13. The method, according to claim 10, further comprising curing thesecond layer.
 14. The method, according to claim 13, in which a catalystis mixed in the second gel coat so as to activate the curing of thesecond layer.
 15. The method, according to claim 6, in which the firstlayer has a thickness ranging from 0.001 to 0.100 inches (0.0254 mm to2.54 mm).
 16. The method, according to claim 15, in which the firstlayer has a thickness ranging from 0.005 to 0.03 inches (0.127 mm to0.761 mm).
 17. The method, according to claim 16, in which the firstlayer has a thickness ranging from 0.01 to 0.02 inches (0.254 mm to0.508 mm).
 18. The method, according to claim 17, in which the firstlayer has a thickness of about 0.014 inches (0.356 mm).
 19. The method,according to claim 12, in which the second layer has a thickness rangingfrom 0 to 0.05 inches (0 mm to 1.27 mm).
 20. The method, according toclaim 19, in which the second layer has a thickness ranging from 0.005to 0.03 inches (0.127 mm to 0.761 mm).
 21. The method, according toclaim 20, in which the second layer has a thickness ranging from 0.01 to0.02 inches (0.254 mm to 0.508 mm).
 22. The method, according to claim20, in which the second layer has a thickness of about 0.015 inches(0.381 mm).
 23. The method, according to claim 13, in which the curingof the second layer takes place for about 30 to 50 minutes.
 24. Themethod, according to claim 23, in which the curing of the second layertakes place for about 40 minutes.
 25. The method, according to claim 2,in which a digital printer is pre-programmed to apply the inks to matchthe second pattern on the mold.
 26. The method, according to claim 10,further comprising applying reinforcement material on the second layerto form a reinforcement layer on the second layer.
 27. The method,according to claim 26, in which the reinforcement material is applied byspraying the reinforcement material over substantially the entiresurface of the second layer.
 28. A decorative panel comprising: a firstlayer defining a front of the decorative panel, the first layer beingclear; a second layer covering substantially the entire surface of thefirst layer; a first pattern located between the first and second layer,the first pattern being digitally printed on one of the first layer orthe second layer and being visible through the first layer.
 29. Thedecorative panel, according to claim 28, in which the second layer isopaque.
 30. The decorative panel, according to claim 28, furthercomprising a reinforcement layer covering substantially the entiresurface of the second layer.
 31. The decorative panel, according toclaim 28, in which the first and second layers define a texturedsurface.
 32. The decorative panel, according to claim 28, in which thefirst and second layers define a substantially smooth surface.
 33. Thedecorative panel, according to claim 28, in which the first patternimitates the appearance of a natural material.
 34. The decorative panel,according to claim 28, in which the first pattern imitates theappearance of a manmade design.
 35. The decorative panel, according toclaim 34, in which the manmade design is selected from a groupcomprising a tiled surface, brickwork and a stone wall surface.